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Track events with ISO 8601 timestamps by wrapping date calls in functions. This ensures consistent, machine-friendly logs across environments.

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Why Use Timestamped Logs

Timestamped entries help you:
  • Debug sequences in real time
  • Audit events in containerized workflows
  • Reconstruct failures across distributed systems

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Quick Demo: Inline Timestamp

Use echo with command substitution to append UTC time: 
echo "$(date -u +"%Y-%m-%dT%H:%M:%SZ") : Script event happening"
Output: 
2023-05-20T03:51:03Z : Script event happening

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Reusable log Function

Instead of repeating timestamp logic, encapsulate it: 
#!/usr/bin/env bash
log() {
    echo "$(date -u +"%Y-%m-%dT%H:%M:%SZ") ${*}" >&2
}

log "Hello World!"
Running ./log.sh produces: 
2023-06-01T05:42:45Z Hello World!
Sending log messages to standard error (>&2) separates them from regular output and integrates better with redirection.
The image features a diagram with a clock icon and connected nodes, accompanied by the text "Enabling us to track the flow and sequence of events," under the heading "Logging."

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ISO 8601 Date Format

Using YYYY-MM-DDThh:mm:ssZ guarantees consistency across locales. Common date specifiers:
SpecifierMeaning
%YYear (4 digits)
%mMonth (01–12)
%dDay of month (01–31)
%HHour (00–23)
%MMinute (00–59)
%SSecond (00–59)
%ZTime zone (e.g., UTC)
Test formats: 
date
date -u +"%Y-%m-%dT%H:%M:%SZ"
# 2023-05-19T15:53:19Z
Avoid over-logging. Too verbose logs can obscure critical information and degrade performance.

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Best Practices

  • Write logs for humans: clear, concise, and actionable.
  • Include only relevant data: timestamps, event messages, and context.
  • Use consistent formatting to facilitate automated parsing.
The image shows a signpost with two directions: "Judiciously and succinctly" marked with a red cross, and "Quality and relevance" marked with a green check.

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